[IGNITE-7015] SQL: Index should be updated only when relevant values changed

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: sql
• Labels: iep-19 performance
• Assignee: Unassigned
• Reporter: Vladimir Ozerov
• Created: 24/Nov/17 13:52
• Updated: 29/Apr/19 17:03

Description

See GridH2Table.update method. Whenever value is updated, we propagate it to all indexes. Consider the following case:
1) Old row is not null, so this is "update", not "create".
2) Link hasn't changed
3) Indexed fields haven't changed

If all conditions are met, we can skip index update completely, as state before and after will be the same. This is especially important when persistence is enabled because currently we generate unnecessary dirty pages what increases IO pressure.

Suggested fix:
1) Iterate over index columns, skipping key and affinity columns (as they are guaranteed to be the same);
2) Compare relevant index columns of both old and new rows
3) If all columns are equal, do nothing.

Fields should be read through GridH2KeyValueRowOnheap#getValue, because in this case we will re-use value cache transparently.

Issue Links

• is duplicated by: IGNITE-7014 SQL: in-place update should be allowed when indexing is enabled
• links to: GitHub Pull Request #3150
• links to: GitHub Pull Request #3150
• links to: TC run